I don't care much for the Aliens setting, and AP looks pretty generic. But still, it's refreshing to see other stuff than the usual fantasy. Hopefully, it'll allow them to off the main fantasy clichés. I also don't care much about the combat system, as long as it's not clunky. What I do care about is roleplaying, and it seems to me that Obsidian is actively trying to improve it, even if the result of a dialogue system like AP uses has still to make its proof.
I believe they realize they cannot compete with FPShooter/Stealth games on the action gameplay front. Hence focusing on dialogues.
For AP, it could become very interesting if they put relationships with main NPCs under pressure with (possible) conspiracy, manipulation, questioning loyalty, chosing sides... I haven't seen many games take this kind of intrigue and make it personal, involve tension with coworkers/friends. Doubt your mission, change side and suddenly you have a crisis on your hands: friends become ennemies, maybe they follow you... There's lots of potential RPG goodness there, I just hope they go all the way in that direction.
Aliens is also interesting, because the game can't be centered on aliens, but rather the effect they have on our minds, mainly fear and how we deal. I sure hope the alien threat makes humans tear each other/each faction appart from fear.
There's potential in those games, and Obsidian looks willing to exploit this depth, which is better than I can say for most devs/publishers out there. I'm optimistic until I know more.